Hi all, Have done a fair bit of rebuilding and putting back to basics on son's yq100, now can't get the damn thing started. we've replaced the crank, new std rings, cleaned head, new plug, new coil, replacement cdi unit, new relay, new starter motor, new rotovator stator, replacement std carb, replacment std airbox, new exhaust, new variator and rollers and belt. think thats all. ok, she did start for a short while after the rebuild but wouldn't run right, complete lack of power til 3500 revs then bang, off she went like a rocket. this happened a few times, then she statrted to not start, turns over now, fires but doesn't catch. Thing I failed to say is that for the above short running and starting, you have to have full choke against the stops and no throttle, any throttle and she just cuts out. we've swapped needles float and jets and carb bodies, and no difference. the needle is set on the middle ring. the jets are the standard what is it now 44 and 75 i think? so, what have i missed, i am baffled. it does seem to be carb related though.... please help, i need to get this back on the road for his new job. martin
When you rebuild an engine you need to pressure test the thing to check for leaks. If it only ran with the choke, the odds are that there is a leak somewhere and that is why it won't run. A pretty big leak by the sound of it. Time to strip down/rebuild. Sorry
Check the crankcase seals. If you've replaced the crank, the worn seals probably won't be sealing against the new crank. Always fit new seals when you split the cases, to not do this is false economy. If you can get an airline onto the vacuum line to the carb, try a pressure test of the crankcase and see if you can detect air getting past the crankcase seals. Also check the gaskets around the reed block - a thin bead of silicone sealant on the gasket faces will make all the difference if you want to prevent induction leaks.
http://www.scootershack.co.uk/threa...ms-on-peugeots-and-yamahas.34074/#post-321774 have a read through this thread
